Rolls-Royce delivers permanent magnet tunnel thruster

SEPTEMBER 20, 2012 — Rolls-Royce has delivered the first of its newly-developed permanent magnet tunnel thrusters (TT-PM) to Norwegian company Olympic Shipping, who will operate the thruster on the Olympic Octopus.

Delivered in 2007, Olympic Octopus is a Rolls-Royce design UT 712 L multifunctional anchor-handling vessel (AHTS). The TT-PM is currently being fitted into the hull.

Rolls-Royce says the TT-PM offers numerous advantages over traditional tunnel thrusters, including a 25 percent increase in power output of from the same size propeller and a significant reduction in noise and vibration. It can be removed underwater, eliminating the need for dry docking.

Anders Almestad, President – Offshore, Rolls-Royce said: “We are delighted that Olympic Shipping is the first customer to select our new tunnel thruster. This cutting edge technology is suitable for a range of applications in offshore and merchant vessels, where operators will benefit from its high power output and rapid response to power demand, combined with exceptionally low noise levels.”

“The new thruster is quiet, efficient and extremely durable,” he continued. “It is capable of running for thousands of hours in intensive operations such as the harsh conditions of the offshore oil and gas fields, where rapidly varying loads and alternating thrust directions are the norm.”

The new thruster design concept comprises a permanent magnet motor in a rim, which drives the propeller in the centre. The permanent magnet motor consists of a stator that carries a number of electrical coil windings, and a rotor fitted with a number of very strong permanent magnets. By having the motor in the rim, this frees up space directly above the thruster where thruster motors are normally located, making the thruster room available for other equipment or alternative use.

A rotating magnetic field is created by the stator which interacts with the fields of the permanent magnets on the rotor, which generates force to drive the rotor around, providing the mechanical power.

Rolls-Royce has put the thruster through an extensive test program, operating it continuously for many months, demonstrating its reliability, enhanced maintainability, performance and operational efficiency.